Piroska

My understanding is that epilepsy can't be cured (please correct me if I'm wrong), but I'm kind of curious because one of my sisters was diagnosed with epilepsy when we were still children (she was in kindergarden at the time I think). She had it for a couple of years, had EEGs and so on, and was put on medication. Years later they stopped giving her the meds, her EEGs were normal and the doctor said we can consider it over (I don't know how he phrased it but that's kind of how my mother put it I think).
They made a big deal out of the meds when she had it (although she never had a seizure) - I remember once when we went on vacation by car, after an 8 hour drive my mother foudn out she had forgotten my sister's meds, so my dad, uncle and sister had to drive all the way back to get them (because we were abroad and could not have gotten a substitute without hospitalizing her). How can epilepsy simply disappear though?